Our laboratory studies Epstein-Barr viral (EBV) DNA replication. We have isolated and characterized a number of virally induced or associated DNA processing enzymes. An intracellular DNA polymerase and an exonuclease have been associated with productive viral DNA replication and are similar to herpes virus-induced enzymes reported in other cell systems. An EB-virion-associated DNA polymerase has been shown to have a repair-type function that is essential early in the replication process. An intracellular endonuclease apparently creates gaps in the viral DNA, and may be a representative of a new class of mammalian endonucleases. We are currently tying our knowledge of these DNA processing enzymes in with studies of replicating viral DNA. We are isolating plasmid and linear EBV DNA replicative intermediates from drug-treated cells. Our goal is to determine the roles of the various enzymes described above in the generation of the various DNA forms observed, using DNA sizing, DNA binding and electron microscopic techniques.